1. Technology Field
The invention generally relates to a memory space management method, and more particularly, to a memory space management method adapted to a rewritable non-volatile memory and a memory controller and a memory storage device using the same.
2. Description of Related Art
Along with the widespread of digital cameras, cell phones, and MP3 in recently years, the consumers' demand to storage media has increased drastically. Rewritable non-volatile memory module is one of the most adaptable storage media to aforementioned battery-powered portable products due to its many characteristics such as data non-volatility, low power consumption, small volume, and non-mechanical structure. A memory card is a storage device which uses a NAND flash memory as its storage medium. Memory card has been broadly used for storing personal important data thanks to its small volume and large capacity.
Because memory storage devices having NAND flash memories as their storage media are usually very small, the possibility of losing such a memory storage device is very high. In order to prevent important data stored in such a memory storage device from being accessed by unauthorized people in case the memory storage device is lost, many encryption and authentication techniques have been developed. For example, a plurality of logical block addresses are configured and mapped to a plurality of physical blocks in a rewritable non-volatile memory module, and these logical block addresses are grouped into a general partition and a secured partition. A user has to pass the identity verification (for example, password or fingerprint comparison) before the user can access data stored in the secured partition. Besides, after the identify verification fails for over a predetermined number, the secured partition is locked and becomes inaccessible. However, after the secured partition is locked, those physical blocks mapped to the logical block addresses in the secured partition cannot be accessed and used anymore, which causes a waste of memory space. Thereby, how to develop a memory space management method that allows the locked secured partition to be re-used has become a major subject in the industry.
Nothing herein should be construed as an admission of knowledge in the prior art of any portion of the present invention. Furthermore, citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention, or that any reference forms a part of the common general knowledge in the art.